Protractor attachment for layout tables



Dec. 27, 1960 G. H. KNAUER 2 Sheets-Sheet 1 GAIL H K/vAuER ATTORNEY'S Dec. 27, 1960 PROTRACTOR ATTACHMENT FOR LAYOUT TABLES Filed Aug. 15, 1958 2 Sheets-Sheet 2 43 H65 43 46 F/G INVENTOR GAIL H K/vA um ATTORNEYS G. H. KNAUER 2,965,968

United States Patent PROTRACTOR ATTACHMENT FOR LAYOUT TABLES Gail H. Knauer, 317 Highland Ave., Beloit, Wis., assignor of small percentages to various assignees Filed Aug. 13, 1958, Ser. No. 754,776

2 Claims. (Cl. 33-76) The present invention relates to protractor attachment for layout tables for checking surfaces of castings.

The primary object of the invention is to provide a protractor attachment for layout tables which can be locked in fixed position on the table and can be angularly adjusted with respect to an object supported on the table.

Another object of the invention is to provide a protractor attachment for layout tables wherein a single adjustment locks the protractor against rotation and locks the protractor in fixed position on the table.

A further object of the invention is to provide a protractor of the class described above in which the protractor is provided with means for locking within the rectangular grooves of the layout table.

A still further object of the invention is to provide a protractor attachment of the class described above which is inexpensive to manufacture, simple to use, and which is exceedingly accurate.

Other objects and advtnages will become apparent in the following specification when considered in the light of the attached drawings, in which:

Figure 1 is a top plan view of the invention shown attached to a layout table.

Figure 2 is a side elevation of the invention illustrated in Figure 1.

Figure 3 is a top plan view of the protractor with the layout table and bar illustrated in fragmentary detail.

Figure 4 is a vertical section taken along the line 4-4 of Figure 3, looking in the direction of the arrows.

Figure 5 is a perspective view of the protractor block.

Figure 6 is a perspective view of the protractor lock.

Figure 7 is an inverted perspective view of the protractor base.

Figure 8 is a view similar to Figure 4 illustrating the protractor lock in locked position.

Referring now to the drawings in detail wherein like reference characters indicate like parts throughout the several figures, the reference numeral 10 indicates generally a protractor attachment for a layout table indicated generally at 11.

The layout table 11 is formed of metal and is relatively thick having a flat upper surface 12 in which are formed a plurality of transversely extending generally rectangular slots 13 and a plurality of longitudinally extending generally rectangular slots 14 arranged perpendicularly to the slots 13. The slots 13, 14 and the table 11 are of conventional form.

The protractor attachment 10 includes a cylindrical base 15 having an annular upstanding flange 16 integrally formed on the peripheral edge thereof to form a cylindrical cup 17. The base 15 has a generally rectangular opening 18 formed therein centrally thereof and provided with a side wall 19 extending perpendicularly to the lower face of the base 15 and with a second opposed side wall 20 which extends at an angle to the lower surface of the base 15 converging upwardly with respect to the side wall 19.

The base 15 is provided with a pair of generallyrrectangular lugs 21 arranged in alignment with the generally rectangular opening 18 at opposite ends thereof. The lugs 21 are aligned with each other and arranged to engage in one of the slots 13, 14 of the layout table 11.

A locking block 22 is seated in the opening 18 and provided with a generally rectangular lug 23 extending below the base 15 in substantial alignment with the lugs 21. The block 22 has a side face 24 arranged adjacent the wall 19 of the rectangular opening 18 and sloping downwardly and outwardly therefrom. The opposite side of the block 22 is provided with an arcuate wall 25 which is arranged for engagement with the upwardly sloping wall 20, as best seen in Figures 4 and 8. A threaded shaft 26 is integrally formed on the block 22 and extends upwardly therefrom above the base 15. The upper edge 27 of the flange 16 is provided with radially extending circular graduations 28, for reasons to be assigned.

A cylindrical plate 29 is seated in the cup 17 for rotational movement therein and is provided with a central bore 30 through which the threaded shaft 26 engages. The cylindrical plate 29 is provided with an annular groove 31 in the peripheral edge thereof for engagement therein of a set screw 32 extending through the flange 16 to releasably secure the plate 29 in the cup 17. The upper end of the bore 30 is provided with a semi-spherical fillet 33, as best seen in Figure 5.

The cylindrical plate 29 has an integral generally rectangular extension 34 positioned slightly above the upper surface 27 of the flange 16 and secured to the upper face of the plate 29, as best shown in Figures 3 and 4. The extension 34 is provided with a depending plate 35 adjacent the edge of the extension 34 opposite the plate 29.

A bevel block 36 is secured to the edge of the extension 34 opposite the plate 29 and is provided with a threaded bore 37, as best seen in Figures 4 and 5.

The bevel block 36 has a rectangular groove 38 extending upwardly therein adjacent the plate 35. A straight edge angle member 39 is provided with an upstanding flange 40 and a generally horizontal portion 41, as can be seen in Figures 3 and 4, with the upstanding flange 40 engaging in the groove 38 where it is clamped by a hand screw 42.

A hand nut 43 is provided with a threaded bore 44 for cooperative engagement with the threaded shaft 26, and the end 45 of the hand nut 43 is formed semi-spherical to engage in the semi-spherical fillet 33. A handle 46 is integrally formed with the hand nut 43 for turning the hand nut 43 to clamp the plate 29 in the cup 17.

In the use and operation of the invention, the protractor 10 is positioned on the surface 12 of the table 11 with the lugs 21, 23 engaged in one of the slots 13, 14 and the plate 29 is revolved until the straight edge 39 is in the desired position. The hand nut 43 is turned by means of the handle 46 and the coaction of the arcuate wall 25 of the block 22 with the sloping wall 20 of the rectangular opening 18 causes the lug 23 to tilt and bind against one side of the slot 14 while the lugs 21 bind against the opposite side of the slot 14 as the nut 43 is tightened. The radius of the arcuate wall 25 relative to the shoulder at the top of wall 24 is such that contact is made with the sloping wall 20 before the shoulder engages the underside of plate 29. With the nut 43 tightened firmly, the plate 29 is locked against rotation in the cup 17 and the protractor 10 is locked to the table 11 to prevent movement therebetween.

The straight edge 39 has a heavy metallic block 47 engaged thereagainst and supported on the surface 12 0f the table 11. A surface gauge indicated in broken lines in Figures 1 and 2 at 48 is used in conjunction with the block 47 to measure the desired surfaces of a casting indicated generally at 49 illustrated in broken lines in Figures 1 and 2. After the desired measurements are made with one setting of the protractor 10, the nut 43 can be loosened and the straight edge 39 moved to another positionfor additional measurements to be made.

Having thus described the preferred embodiment of the invention, it should be understood that numerous structural modifications and adaptations may be resorted to without departing from the scope of the appended claims.

What is claimed is:

1. A layout protractor attachment for tables of the type having a plurality of generally rectangular slots formed therein comprising a base supported on said table, lugs integrally formed in depending relation on said base for engaging in the rectangular slot of said table, said base having an opening therein having a substantially vertical side and an upwardly and inwardly inclined side positioned between said lugs, a cylindrical plate, means IO- tatably mounting said plate on said base, a straight edg means releasably securing said straightedge to said plate, and means cooperating with the lugs on said base for simultaneously releasably locking said plate to said base and releasably locking said base to said table, said last mentioned means comprising a movable lug having a substantially straight side and an arcuate side cooperating with the inclined side of said opening and a depending rectangular tongue extending into the rectangular slot of the table, said lug being positioned in said opening between the lugs on said base, and means for tilting said movable lug oppositely ofthe lugs on said base to positively engage opposite sides of the slot in said table and the opening in said base.

2. The structure of claim 1 wherein said last mentioned tilting means includes a threaded extension on said movable lug, and an operating handle threadedly engaging said extension positioned on the upper side of said cylindrical plate.

References Cited in the file of this patent UNITED STATES PATENTS 145,354 Loestscher Dec. 9, 1873 1,001,631 Gardner Aug. 29, 1911 2,768,444 Gaut et al Oct. 30, 1956 FOREIGN PATENTS 105,711 Sweden Oct. 13, 1942 

